1. Field of the Invention
The present invention relates generally to a leveling motor and, more particularly, to a leveling motor configured to remove a gap from a threaded portion converting a rotating force of the leveling motor into an axial feeding force, thus minimizing a movement error and enabling precisely controlled leveling operation.
2. Description of the Related Art
Generally, a luxury vehicle is equipped with a headlamp leveling device to adjust an irradiation angle of a headlamp according to a change in position of a vehicle body.
Such a headlamp leveling device functions to adjust the irradiation angle of light by pushing and pulling a reflector using a predetermined drive means. Such a drive means is a leveling motor of the headlamp leveling device.
FIG. 1 is a side sectional view showing a conventional leveling motor, and FIG. 2 is an enlarged side sectional view showing a threaded portion of a shaft of the leveling motor.
A motor 10 largely includes a housing 20 receiving parts driven by electromagnetic force, a device accommodated in the housing 20 and driven by the electromagnetic force, and a shaft 11 axially moving out of the housing 20 to adjust an irradiation angle of a lamp.
An upper end of the shaft 11 protrudes upwards from the housing 20. The shaft 11 is supported in the housing 20 to be moved up and down by a threaded pipe 21.
To be specific, a threaded portion 12 is formed on a predetermined portion of an outer circumference of the shaft 11, and the threaded pipe 21 is disposed to surround an outer circumference of the shaft 11 and has a grooved portion 22 to correspond to the threaded portion 12.
If the threaded pipe 21 rotates, the screw-shaped threaded portion 12 formed on the outer circumference of the shaft 11 vertically moves along the grooved portion 22.
However, a gap (d) exists between the threaded portion 12 and the grooved portion 22. Such a gap (d) causes a movement error in an axial direction.
FIG. 2 shows the gap in detail. A root of each thread of the threaded portion 12 is in close contact with a groove. Thus, a crest of the thread is spaced apart from the groove in an axial direction. Here, if the threaded pipe 21 provides a downward feeding force for the shaft 11, a backlash occurs in proportion to a distance in which the groove is to move to come into contact with the crest of the thread.
Such a gap causes the movement error of the leveling motor, thus making it difficult to precisely control the irradiation angle of the headlamp.